acetophenone

Pmcess Contm le Plant In, tmls for Acetophenone Production

, 0 0 0

HOWARD J. SANDERS Assmiate Editor

in mllaboration with

HARRk r . n u G HOWARD S. McCULLOUGH Carbide and Carbon Chemicab Co., Institute, W. Va. Carbide and Carbon Chemieab Co., Neu York, N, Y.,

SOLVENT, a hypnotic, a perfume, a raw material for the A synthesis of tear gas, an intermediate in the production of ncae drops-thk is acetophenone. Never a big-tonnage chemical, acetophenone nonetheless is one of those fundamental organic compounda that for yeam hm been playing an increasingly important role in the U. 8. chemical industry.

Today, the nation’s largest Single producer of acetophenone is Carbide and Carbon Chemicals Go., a division of Union Carbide and Carbon Cop. Actually, the production of acetophenone by Carhide iS a direct outgrowth of its manufacture of styrene. In Carbide’s procese, involving the stepwise conversion of ethylbenzene to styrene, crude acetophenone is one of the principal intermediatea. Periodically, a portion of this intermediate is withdrawn from the process and refined to commercial grade acetophenone.

Carhide’s interest in styrene and thus in acetophenone began in the t b i i e s . As early 88 1936, Carhide was seriously consider-

ing the commercial production of s t y r e n e i n line with the company’s long-standing intereet in resins and plaetica. Then in * 1939, the parent company, Union Carbide and Carbon Corp., acquired the Bakelite Corp. This move provided additional impetus for Carhide’s manufacture of styrene, since the prcduc- tion of polystyrene plastics by the Bakelite COT. could be c83c ried out with greater efficiency and economy if styrene were produced within the Carbide organization.

Carbide’s research on the synthesis of styrene by a variety of techniques WBB already in progress. In June 1941, a pilot plant was completed for the production of styrene from ethylbensene via acetophenone. Signilicantly, the selection of thin synth& was strongly inlluenced by Carbide’s confidence in the commercial pwihilities both for acetophenone and phepvlmethylcarbinol- the other important intermediate in the proc.eea. The pilot plant development of Carbide’s styrene p r m was

moving ahead rapidly when, on December 7, 1941, the Japanese

2

January 1953 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 3

struck at Pearl Harbor. In a matter of months, the U. S. Govern- ment began doubling, trebling, and quadrupling its demands for styrene-a necessary raw material, with butadiene, for the manufacture of GR-S.

By that time, Carbide had already begun construction of a full-scale (12,000 tons per year) styrene plant a t South Charles- ton, W. Va., primarily for use in connection with Carbide's manufacture of plastics. Because of the nation's acute need for styrene, however, the company abandoned this plan and, instead, signed a contract with Rubber Reserve Co. to build and operate integrated butadiene and styrene plants 7 miles away a t Institute, W. Va. Less than 10 months after construction had begun on both plants, Carbide was shipping butadiene and styrene to the neighboring government-owned polymer plant, operated by U. S. Rubber Co., for conversion to GR-S. Carbide purchased the butadiene and styrene plants from Rubber Re- serve in June 1947.

Because of the nation's sizable postwar demand for styrene and its relatively modest requirements for acetophenone, Carbide found no immediate need after World War I1 to process any part of its crude intermediate to refined acetophenone. In January 1949, Carbide launched its first commercial production of the refined material. I n so doing, Carbide entered into the manufacture of an organic compound which, like many another ketone, has a host of useful properties and a long and varied history.

Until 1949, Commercial Acetophenone Was Produced Primarily by Friedel-Crafts Reaction

Acetophenone (also variously known as phenyl methyl ketone, acetylbenzene, and hypnone) is the simplest of the ketones containing both an aromatic and aliphatic group. It is a colorless liquid with a sweet, pungent odor. The compound crystallizes in the form of large plates and;although only slightly soluble in water, dissolves readily in alcohol, benzene, ether, or chloroform. Its physical properties are indicated in Table I. Acetophenone is present in the heavy-oil fraction of coal tar boiling at 160' to 190' C. and is found in nature in oil of castoreum, obtained from beavers; oil of labdanum, recovered from plants; and in the buds of balsam poplar (16).

s,

TABLE I. PROPERTIES OF PURE ACETOPHENONE Molecular weight Specific gravity at 2O0/ZO0 C. Average weight at 20° C., lb./gal. Boiling point at0760 mm. Hg, O C. Freezing point, C. Refractive index at 20' C. nD Vapor pressure at 20' C., mm. Hg Viscosity at 20' C., op. Solubility in water at 20° C., wt. % Solubility of water in at 20° C., wt. 7% Specific heat at 10.3' C., B.t.u./lb./' F. Heat of vaporization at 760 mm. Hg, B Coefficient of expansion at 20' C./' C. Flash point, Cleveland open cup, F.

.t.u ./lb.

120.14 1.030 8.57 201.7 19.7 1.5363 0.3 1.84 0.55 1.65 0.474 139 0.00084 205

The first synthesis of acetophenone was carried out in 1857 by the French chemist, Charles Friedel, who prepared the compound by treating calcium benzoate with calcium acetate (12 ) . In 1885, Dujardin-Beaumetz and Bardet discovered that acetophenone could be used as a hypnotic-hence the name, hypnone. Some years later, as hypnotics more positive in their action were introduced, acetophenone was largely replaced in this application by other compounds.

Since its first preparation in 1857, a number of alternate procedures have been worked out for the synthesis of acetophenone. However, because of high cost, low yields, or other fac- tors, only a few of these syntheses have ever attained commercial status.

%

Among the better known reactions are: 1.

2.

Benzene and acetyl chloride in the presence of aluminum

Benzene and acetic anhydride in the presence of aluminum chloride ( 1 )

chloride ( 2 )

3. Ethylbenzene and oxygen in the presence of manganese

4. Benzoyl chloride and zinc dimethyl (25) 5. Acetic and benzoic acids in the presence of manganese

6. Styrene chlorohydrin and steam in the presence of an

7. a-Chlorostyrene and aqueous sulfuric or hydrochloric

8. a-Methylstyrene and oxygen in the presence of a nickeI

acetate catalyst (24) or chromium eesquioxide catalyst (21 1

oxide or thorium dioxide catalyst (26 )

aluminum oxide catalyst (6)

acids ( 5 )

oxide, iron oxide, or vanadium oxide catalyst (4) - P R O D U C T I O N

0 PRICE F O R PERFUMERY. GRAOE

+ROOUCTION, POUNDS

350,000

PRICE, I "04 1 de*,

- 2 .20

- 2 .00

- I80 - 1.60

Figure 1. Production and Prices of Acetophenone- 1934-1951

During World War I and earlier, the bulk of the acetophenone available in the U. S. was imported. I n 1925, the Givaudan Corp., in Delawanna, N. J., began manufacturing the compound b3 the Friedel-Crafts reaction of benzene and acetic anhydride. Until Carbide entered the picture, this company was the nation's leading producer of acetophenone. Another manufacturer a t present is Trubek Laboratories, Inc., East Rutherford, N. J., which began synthesizing the compound by the Friedel-Crafts reaction of benzene and acetyl chloride in 1932. Trubek has been in a particularly favorable position to use this synthesis since it is itself a producer of acetyl chloride.

In a typical plant procedure for the manufacture of acetophenone by the Friedel-Crafts reaction ( l 7 ) , 100 pounds of acetic anhydride are gradually added to a jacketed, agitated kettle containing 380 pounds of'dry benzene and 417 pounds of anhydrous aluminum chloride. Cold water or brine is circulated through the jacket to maintain the reaction temperature below 50" C. The hydrogen chloride liberated by the process is conducted to a stoneware absorption system. After the full amount of anhydride has been added over a period of an hour, the charge is refluxed for about 20 hours or until the evolution of hydrogen chloride has practically ceased.

The charge is then cooled with ice or ice water to 25' C. Both the aluminum compounds and the acid are removed from the benzene layer by first washing with water, then with dilute sodium hydroxide, and again with water. Next, the benzene layer is distilled under vacuum of 20 mm. of mercury to give 200 pounds of commercial grade acetophenone or 85% of the theoretical yield. Purer acetophenone can be obtained by crystallization of the commercial material.

As a new development, acetophenone may be made available as a by-product from the phenol-from-cumene process devised by Distillers Co., Ltd., of Great Britain and independently in this country by Hercules Powder Co. In this process, cumene is oxidized to cumene hydroperoxide, which, upon acidification, yields phenol and acetone. I n addition, about 3 to 5% of the cumene charged is converted to acetophenone. Currently, Hercules is building a phenol plant near Paulsboro, IS. J., to em- ploy this process. Other U. s. companies planning to use this synthesis include Standard Oil Co. of California at Richmond,

4 I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY Vol. 45, No. 1

Calif., and the Barrett Division of Allied Chemical & Dye Corp. a t Frankford, Pa.

Production of Acetophenone Continues Upward Swing

Over the years, the total U. S. production of acetophenone has increased steadily. According to the U. S. Tariff Commission, output has risen from 6686 pounds in 1934 to 16,585 in 1937, 27,500 in 1941, and 57,200 in 1948 (28). More recent statistics are not available officially, although production in 1951 has been estimated a t approximately 350,000 pounds (Figure I).

aluminum chloride or aluminum t-butoxide (11). An unusual property of dypnone is its pronounced ability to absorb ultraviolet light. 9 0.000004-inch coating of dypnone, although transparent to visible light, prevents the passage of over half of the incident ultraviolet. However, because dypnone stings the skin of some people, it is not used in sun-tan lotions.

For several years, Winthrop-Steams, Inc., has marketed Neosynephrine (Phenylephrine : 1-or-hydroxy-p-methylamino-3- hydroxy-1-ethylbenzene), which can be made from acetophenone (19) . This drug, a vasoconstrictor, is used as an active ingredient in nose drops. Other pharmaceuticals that may be derived from

acetophenone include Chloromycetin (chloramphenicol), the antibiotic syn- thesized by Parke, Davis & Co. (20) ; Decapryn (Doxylamine; dimethyl- aminoethoxy methylbenzyl pyridine), an antihistamine manufactured by William S. Merrell Co. (27) ; and Ar- tane (Trihexiphenidyl; 3-(N-piperidyl)- 1 -phenyl - 1 - cyclohexyl - I -propanol), Lederle Laboratories’ antispasmodic for the treatment of palsy ( 3 ) . Other possible derivatives of acetophenone are mandelic acid (a-hydroxyphenyl acetic acid), a urinary antiseptic ( I O ) , and cinchophen (2-phenylquinoline- 4-carboxylic acid), an analgesic and antipyretic (16).

Partial reduction of acetophenone results in the formation of phenylmethylcarbinol, of value as a perfume and aolvent. The phenylurethaneof phenylmethylcarbinol is a soporific, while phenylmethylcarbinyl acetate is a per-

General View of Reaction Side of Styrene Unit fume base for the gardenia odor. Oxidation reactors are in center and blowoff recovery equipment in left foreground Various applications for aceto-

Mounting U. S. production of acetophenone has been accom- panied by a general decline in prices. Specifically, the price of perfumery grade acetophenone per pound has fallen from $3.25 in 1930 to $1.60 in 1940 and to $1.30 in 1950. Since Carbide began producing refined acetophenone several years ago, its price has remained a t $0.75 per pound for the commercial grade.

Indications are that, as acetophenone production continues to rise in response to increasing demand, the price of acetophenone will decline still further, Assuming a considerable increase in demand and no radical changes in manufacturing technology, the price of acetophenone may eventually approach that of styrene, which at present sells for about $0.21 a pound.

Compound Is Used Extensively in the Preparation of Perfumes

Traditionally, one of the most prominent uses for acetophenone has been in the preparation of perfumes. Various perfumes pos- sessing the odors of honeysuckle, jasmine, hawthorne, or new- mown hay contain acetophenone (18). Today, this ketone finds increasing use in soap perfumery and as an additive for masking the odors of paints, paint removers, disinfectants, cleaners, and leather finishes.

Another use for acetophenone is in the preparation, by direct chlorination, of w-chloroacetophenone. This derivative, popu- larly known as tear gas, finds use in mob dispersal (9). Dur- ing World War 11, the armed forces called for large quantities of w-chloroacetophenone for the training of troops in the use of gas masks.

Also important is the application of acetophenone in the synthesis of dypnone (phenyl-or-methyl styryl ketone) by the condensation of two molecules of acetophenone in the presence of

phenone may -depend on the compound’s solvent properties. For ex-

ample, acetophenone is suggested as a solvent for the dudges and gums formed in automobile engines or for the inks used in stamp pads and ball-point pens. The compound may also serve as a solvent in paints, lacquers, and varnishes.

Acetophenone and formaldehyde combine in the presence of ammonium chloride to yield two resin-forming compounds, monomethylolacetophenone and trimethylolbisacetophenone. These derivatives can be converted to vinyl phenyl ketone, which sets to a resinous mass. When acetophenone ia treated with formaldehyde and potassium hydroxide, a flexible, infusible resin is formed.

Three Parts of Molecule May Be Involved in Chemical Reactions

Except for the fact that acetophenone does not undergo bisul- fite addition, it exhibits all the standard chemical characteristics of a conventional methyl ketone. As such, its reactions may in- volve any one or more of three parts of the acetophenone molecule: the methyl group, the carbonyl group, or the benzene ring.

Typical of reactions involving the methyl group is the oxidation of acetophenone with selenium dioxide to form phenylglyoxal (10). Halogenation of the methyl group leads to the formation of mono-, di-, or trihalogenated derivatives.

Reactions of acetophenone involving the carbonyl group include the reduction of the ketone to phenylmethylcarbinol. The Clemmenson reduction of acetophenone in the presence of amal- gamated zinc and hydrochloric acid results in the formation of ethylbenzene ( 7 ) . The Grignard reaction of acetophenone and phenyl magnesium bromide can be used in the preparation of a,a-diphenylethylene (8). Another reaction involving the car-


Feed Ethylbenzene feed tanks (2) Catalyst feed tanks (2 )

Oxidation reactors

First blowoff condenser

Oxidation

Second blowoff condenser

-2' C. condenser

Decanter Caustic and water wash

Crude product cooler

Caustic feed tanks 2) Caustic settling tank Water scrubber

Ethylbenzene stripping still feed tank

Distillation Ethylbenzene stripping still

Ethylbenzene stripping still reboiler

Ethylbenzene stripping still condenser

Acetophenone-oarbinol refining still

Acetophenone-carbinol refining still

Acetophenone-carbinol refining still

Acetophenone-carbinol receivers (2) Batch residue stripping still

Batch residue stripping still receivers

reboilers (2)

condenser

(2)

Feed Acetophenone-carbinol feed tank Catalyst-feed mixing tank

Dehydrogenation Dehydrogenation reactor Dehydrogenation reactor condenser

Dehydrogenation reactor receivers (2)

Distillation Batch kettle Batch column

Batch column condenser

Batch column intermediate receiver Batch column product receiver

TABLE 11. PROCESS EQUIPMENT Dimensions, Design Operating Operating

Square Capacity, Pressure, Pressure, Temperature, Feet Gallons Pounds Pounds O c.

Production of Mixture of Acetophenone and Phenylmethylcarbinol I.

... 440

172

108

. * . 433

I . .

36-inch diam. X 20 feet high ...

120-inch diam. X 19 trays

812

1,450

120-inch diam. X 19 trays

585 (,each)

880

. . . . . .

. . .

iio . . .

88-inch &am. X 24 trays

1,380

. . . ...

12,000 600

5,400

... . . . . . . 500

. . . 1,500 7,500

7,500

. . .

. . .

. . .

...

. . .

. . .

... 6,000

800

500

Atm. 30

65

75

75

75

75

100

100 30 80

30

30

300

30

30

300

30

25 30

30

Atm. Atm.

30

29

28

26

26

35

Atm. Atm. Atm.

Atm.

85 mm. Hg abs.

175 (steam, shell)

5 (shell)

14 mm. Hg abs.

170 (steam, shell)

5 (shell)

Atm. 100 mm. Hg abs.

100 mm. Hg abs.

11. Acetophenone Purification

10,000 25 Atm. 500 30 Atm.

500 30 Atm. . * . 30 5 (shell)

500 30 Atm.

15,000 25 110 mm. Hg abs. . . . 25 35 mm. Hg abs.

. . . 30 35 mm. Hg abs.

10 OOQ 30 35 mm. Hgabs. 1O:OOO 30 35mm. Hgabs.

5 (shell)

Atm. Atm.

126

55 (outlet)

30

0

55

126 (inlet) 45 (outlet)

Atm. Atm. Atm.

Atm.

145 (base)

. . . 30 (water)

148 (base)

... 30 (water)

Atm. 170

Atm.

Atm. Atm.

200 35 (outlet)

Atm.

160 110

35

Atm. Atm.

Materials of Construotion

Steel 347 stainless steel

Steel brick-lined with 347 stainless stekl sleeves, nozzles, etc.

347 stainless steel tube sheet and head 304 stainless steel tubes, cast-:ron shell

347 stainless steel tubea and head, steel shell

347 stainless steel tubes and head, steel shell

347 stainless steel

High-chrome iron

Steel Steel Steel

Steel

347 stainless steel

347 stainless steel heads and tubes,

347 stainless steel heads, admiralty

347 stainless steel

347 stainless steel heads, copper

347 stainless steel heads, admiralty

steel shell

tubes, steel shell

tubes, steel shell

tubes, steel shell Steel 347 stainless steel kettle and anchoi-

type agitator, steel jacket for tetralin

Steel

Steel Steel, agitated

Steel jacket anchor a itator Steel shell ' and heais, admiralty

Steel tubes

Everdur, internal copper coils Copper

Steel shell, bronze heads, admiralty

Steel Steel, resin-lined; stainless steel

tubes

coils

bony1 group is the replacement of the oxygen atom with two chlorines by treatment with phosphorus pentachloride (19).

Typical of substitution reactions in the benzene ring is the nitration of acetophenone with mixed acid to yield m-nitroacetophenone and a lesser proportion of the ortho isomer (IO). Under suitable conditions, chlorine can likewise be substituted in the benzene ring.

Carbide's Acetophenone Is Inter- mediate in Continuous Styrene Process

Before mention is made of the specific chemical reactions involved in Carbide's manufacture of acetophenone, it would be well to indicate first how this process fits in with Carbide's over- all styrene operations. In essence, Carbide's styrene process (Figure 6) consists of four continuous steps:

Aluminum chloride

UD to 125 lb./sa. inch

catalyst - c I I > c 2 H 5 cz> + ''HZ 80Oto 130" C: I -

Benzene Ethylene Ethylbenzene (1)

(71> CzHb

Ethylbenzene

Manganese acetate

up to 50 lb./sq. inch + O2 115' catalyst to 145' C;: + O O C H a + HzO

Acetophenone (2)

( r>COCH, + Acetophenone

Copper-chrome-iron catalyst (IS, 24, SO, Sf)

H2 150'C.; up to 150 lb./sq. inch

~ C H O H C H ~

Phenylmethylcarbinol (3) Titania (II)CHOHCH~ catalyst 2500 c.; (86) + C I > C H = C E + H2O

atmosuheric pressure

Pheny Imethylcarbinol Styrene (4)

I n the alkylation step, ethylbenzene is not the only reaction product; also formed are various polyethylbenzenes. These by- products are recycled to yield more ethylbenzene on dealkylation with excess benzene (11). In the subsequent oxidation step, the reaction products include not only acetophenone and water, but also phenylmethylcarbinol and small percentages of acids and condensation products.

Vol. 45, No. 1 . INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y


x

Feed Control Station Located at Side of One o f the Stills in Styrene Process

The fundamental reaction in Carbide’s synthesis of acetophenone is the oxidation of ethylbenzene in the presence of a manganese catalyst, as indicated in Reaction 2. Three other reactions are also involved:

Manganese aoetate

up to 50 Ib./sq. &h ( ~ > c ~ H ~ + l/zol l15;z;$ . - C_T)CHOHCH~ Ethylbenzene Pheri~lmethylcarbiriol ( 5 )

Manganese acetate D C J & + 302 1150 catalyst to 145q=+ C T > C O z H + COZ

u p to 50 Ib./sq. inch + 2H20 Ethylbenzene Benzoic acid (6)

c Phenylmethylcarbinol Acetophenone (7)

Reaction 5 occurs siniultarieously with the formation of acetophenone; Reaction 6 is a minor side-reaction; and Reaction 7 is a step in the final purification procedure.

Indications are that the oxidation of ethylbenzene proceeds through the formation of an unstable peroxide capable of deconi- posing to form acetophenone and phenylmethylcarbinol. An- other possible reaction route is the. direct oxidation of ethylbenzene to phenylplethylcarbinol, which, in turn, is further oxidized to acetophenone. However, this latter reaction does not predominate since phenylmethylcarbinol is not readily oxidized to acetophenone under the conditions prevailing in the reactor.

In its broadest outline, Carbide’s acetophenone process is divided into two main phases. One of these consists primarily of the oxidation of ethylbenzene to a mixture of acetophenone and phenylmethylcarbinol. The second phase involves the conversion of a portion of the phenylmethylcarbinol to acetophenone and the subsequent separation of refined acetophenone by fractionation. The first phase takes place continuously as an integral

4

part of Carbide’s styrene operations. The second phase is carried out intermittently whenever the production of refined acetophenone is required.

When the equipment employed in the second phase of the operation is not needed for acetophenone production, it can be used instead as miscellaneous recovery equipment for the over- all styrene process. However, a t a future date when the need arises for the full-time production of acetophenone a t Carbide, this equipment will be made available exclusively for acetophenone manufacture. In this way, Carbide will be able to produce annually many millions of pounds of the commercial grade material.

The first phase of the acetophenone process can be conveniently subdivided, for purposes of description, into four major steps: leed, oxidation, caustic and water wash, and distillation. The second phase can be subdivided into three steps: feed, dehydrogenation, and distillation. These operations are diagrammed in the accompanying flow sheets, Figures 2 and 3. The dimensions, capacities, design pressures, operating pressures, operating temperatures, and materials of construction of the plant equipment are summarized in Table 11.

Oxidation Step Yields Mixture of Acetophenone and Phenylrnethylcarbinol

Recycle ethylbenzene obtained from the ethylbenzene stripping still (employed in a later step) is pumped a t the rate of 1300 gallons an hour into the recycle ethylbenzene feed tank. This in- coming stream consists of ethylbenzene and traces of entrained water. The water that settles to the bottom of the tank is discharged to the waste disposal system. The organic layer over- flows to the ethylbenzene feed tank. To this tank is also added make-up ethylbenzene a t the rate of about 500 gallons per hour. This make-up material is essentially pure, dry ethylbenzene. The feed system also includes two catalyst feed tanks that supply a

.

Two 5000-Gallon Oxidation Reactors

N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 45, No. 1

15% aqueous solution of mnganeae acetate to the & E t oxidation r e a c h through a proportioning pump.

Ethylhensene is pumped from the feed tad to the top of the 6rat oxidation reactor at a rate of about ls00 gallons an hour. The catalyst eolution is added simultaneouely. The air required for oxidation enten the bottom of the 6rat reactor thmugh a sparge pipe at the rate of about 35,000 cubic feet an hour. Thia air, at ambient temperstureg, is mpplied at a praasure of 60 pounds per square inch.

The oxidation ia carried out at 30 pounds per square inch preb mm and at 126- C. The termperature of the exothmh reaotion is oontmlled by cooling coils through whioh rim water is circulated at about 30' C. The mtad time of the oxygen and &,hylbnwne is about 1.5 houn. The reaotor ita& in a steel shell with an acid-resbbnt brick

lining (Figure 4). The unit hss three helid, -ded mlingcdamsdeof heat-treated Typs304l ts io lessl . Each of the three coib hao a cooling &ace of 1M) quam fe& The a h , wk, manholes, and manhole disk linm are msde of Tvoe347Lltd&a3.

by-products. At the conversion level of 26%, approximately 88% of the ethylbenzene is converted to scetophenone and phenylmethylcarbinol after repeated recycling. On the other hand, if a much higher singlepass conversion level were selected, the convemion of ethylbenzene would be considerably lees than @3% after repeated recycling.

The exit gaees from both oxidation resotom paae through Stsin- less steel vapor lines to separate atainlese stael entrainment sepsratora The gases are then combined into a single stream and sent to the blowoff reeovery system. Thia 8ystem permits the almcmt oomplete recovary of the organic components of the exit gas and, at the name time, minimieee atmwheric pollution. hs the gaa leaves the reactom, it is aaturated with ethylbenzene, acetophenone, phenylmethylcarbinol, organic acids, and water. Mainly, however, this gas conaista of a noncondenasble fraction mntaining about 0.6% oxygen, 0.4% carbon dioxide, and 99% nitrogen.

In the recovery system, the gas paaees through a water-cooled condenser that reduces the gas temperature from &out 1%' to 55' C. In thia mndenmr, sa &where in the proceaa, the water ..

In series with ths h a t reactor in an identical mcond unit. In this eeeond unit, operating mnditiona are ementisllg the eame IYI

thom m the 6&, except for the hot lhst the air is admitted at a rate of about a0,OOO oubic feet an hour rather than 36,oaO. Tbe um of two reactma in saries inatead of a single double-ekd reactor permits unusually .high ,e rates to be attsined the first reactor becrruse of its low CouOeDtration d oddation products. In the 6rat reactor, about 113% of the inooming e t h y l w e is

con& to totel oddstion p m d k ~ . In the -d reeotor. an additional 10% of the e t h y l w e undergoen oxidation, bringing the total m n d o n to about 26% lhis relatively low conversion level is maintained for the dual pwpose of achieving high reaction rates and of minimking the formation of unmntcd

ueed ia river water. The condensate from the gas stream goes to R decsnter, from which the top organic layerjs returned by gravity to the firsst oxidation reactor. The bottom layer is diachmd to the waatswater disposal line. Thin bottom layer conlaion much of the water formed during the reartion and the water that enwm the reaetor with the catalyst.

The vapor goes to a eeoond water-cooled condenser that reduces its temperature from about 5 5 O to 30' C. Finally, the &as stream is cooled M about 0' C. in a methanoLwater condenser iuaintaioed at -ao C. Aiter paasing through an entrainment

. qmrator, the coodensate from this gaa stream is fed M the cawtic wssh system. The nonrondenllable fraction, composed almmt entirely of nitmgen. ia diwhargd to the atmosphere.

c

9 January 1953 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y

CausLic Neutralizes hboui 98% of Acid Formed during Oxidation

The product from the second reactor, containing about 73% ethylbenzene, 17% acetophenone, 8% phenylmethylcarbinol, and 2% residues and mixed acids, goes to the crude product cooler, where its temperature is lowered from about 126' to 45' C. The liquid stream then passes to the caustic settling tank. Along the way, the crude material is treated with a 10% solution of aqueous sodium hydroxide that enters the system through a caustic feed tank, a proportioning pump, and an injection nozzle. This nozzle, resembling a Pitot tube, is designed to minimize the formation of an emulsion and to prevent fouling by the spent catalyst.

The caustic neutralizes about 98% of the acid formed during the oxidation step. Incomplete neutralization is deliberately employed to keep the crude material on the acid side. This minimizes the formation of acetophenone condensation products that would otherwise build up under alkaline conditions. The slight acidity also reduces the tendency of the organic and aqueous phases to emulsify.

The bottom aqueous phase from the caustic settling tank, consisting largely of spent caustic solution and catalyst, is stripped of organic material by steam distillation and is then pumped to the waste disposal system. The recovered organics are subsequently recycled to the still feed tank employed in a later process step. The top organic layer from the settling tank is pumped to a countercurrent water scrubber that washes out small amounts of entrained caustic. The wash water is sprayed in at the top of the scrubber, while the organic material enters through a bottom sieve plate. The aqueous phase is discarded, and the organic layer passes to the still feed tank.

In addition to this overflow, the still feed tank receives two separate streams from the distillation step involved in the final recovery of acetophenone. One of these streams is a mixture of phenylmethylcarbinol and acetophenone that is collected as the residue from the batch kettle used in acetophenone recovery. The second stream is a mixture of ethylbenzene and acetophenone from the intermediate receiver associated with the same batch still. The still feed tank to which these streams are pumped contains a bottom standpipe to prevent the transfer of trace quantities of an aqueous phase to the ethylbenzene stripping

-

sr

c

il

BLOWOFF N O Z Z L E 7

LIQUID L E V E L i INDICATOR

SAFETY VALVE N O Z Z L E 7

COOLING \ I r N O Z Z L E

€THY L BENZEN E FEED NOZZLE CATALYST-

LIQUID LEVEL INDICATOR

$IR SPARGER

p-SUPPORT

NOZZLE

Drum Loading of Acetophenone in Shipping Department

still, where a t elevated temperatures this aqueous material, if alkaline, would promote the formation of unwanted condensation products.

Ethylbenzene Is Recycled; Acetophenone and Phenylmethylearbinol Mixture Is Refined

The combined organic material in the still feed tank is pumped a t the rate of 1900 gallons per hour through a feed preheater to the ethylbenzene stripping still. This column is controlled at 85 mm. of mercury absolute pressure by means of a two-stage steam jet ejector into which nitrogen is bled continuously. Vacuum operation permits the use of relatively low distillation temperatures that minimize the formation of unwanted residues. The

STEEL SHELL AND NOZZLE

STAINLESS S T E E L SLEEVE-'

P IPE, ETC.

NOZZLE AND MANHEAD

SLEEVE D E T A I L

HOLES DRILLED ON BOTTOM SIDE OF EACH

n S P l D E R L E G 7

Figure 4. Oxidation Reactor

U AIR SPARGER D E T A I L

bottom of the still is operated at about 145' C., while the temperature a t mid-column is controlled at about 1 0 4 O C. Heat is supplied through a steam-heated reboiler. In this reboiler, as elsewhere in the process, steam is used a t a pressure of 200 pounds per square inch.

The distillate, consisting mainly of ethylbenzene, passes through a condenser and then to a decanter, where traces of water are removed. Part of the distillate is returned to the column as reflux a t a rate of 2000 gallons per hour. The ethylbenzene product is pumped at 1300 gallons per hour to the recycle ethylbenzene feed tank employed in the first step of the procese.

The bottom product from the ethylbenzene stripping still, consisting of about 65y0 acetophenone, 31% phenylmethylcarbinol, and 4% residue, is pumped at 600 gallons per hour to the acetophenone-carbinol refining still. In this refining unit, operated a t 14 mm. of mercury absolute pressure, the residue is removed. Vacuum is supplied to the unit by a three- stage steam jet ejector. Heat is furnished by two steam-heated reboilers that maintain a temperature of 148' C. a t the bottom of the column and 125' C. a t mid-column.

10 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 45, No. 1

The mixture of 68% acetophenone and 32% carbinol from the product receivers is collected as needed in a feed tank and from there is pumped continuously during a run to a catalyst-feed mixing tank a t a rate of 120 gallons per hour. To this agitated tank, small quantities of powdered catalyst arc added hourly through a manhole.

At a rate of about 120 gallons per hour, the acetophrnone-carbinol mixture plus catalyst is pumped to the dehydrogenation reactor (Figure 5 ) . This 500- gallon steel vessel, agitated with an anchor-type stirrer, is heated to 200' C. by a jacket containing tetralin. Nitro- gen is sparged into the vessel to sweep out the evolved hydrogen and to reduce the formation of ethylbenzene. The maximum rate of nitrogen addition is governed by the ability of the condenser to cool the effluent gas to about 35" C. After passing through a condenser, the noncondensable gas (mainly hydrogen and nitrogen), is discharged to the atmosphere, while the condensate is collected in a pair of product

Top View of 120-Inch Diameter Acetophenone-Carbinol Oxidation System

Twin reboilera am shown a t lower left

The distillate from the refining still is refluxed a t 750 gallons per hour, while the overhead product is taken off at 475 gallons an hour. This material, composed of about 68% acetophenone and 32% phenylmethylcarbinol plus traces of ethylbenzene and acid, is pumped to a pair of product receivers. The mixture collected in these receivers is the end product of the first phase of the acetophenone process.

Periodically, the bottom product from the acetophenone- carbinol refining still is stripped in a batch residue stripping still. This is the only operation in the first phase of the acetophenone process that is not continuous. The residue stripping still, heated by a jacket containing tetralin, is operated at 170" C. and 100 mm. of mercury absolute pressure. The residue is later used as fuel in the powerhouse, and the distillate, containing acetophenone, carbinol, light residue, and traces of acid, is returned to the system near the caustic injection point.

Purification Includes Dehydro- genation and Further Distillation

The second phase of the acetophenone proccss overcomes thc difficulty that would otherwise be encountered in the attempted separation of a mixture of 68% acetophenone and 32% phenylmethylcarbinol by straight fractionation. The satisfactory recovery of refined acetophenone from a mixture at this concentration requires an impractically large number of plates At atmos- pheric pressure, the boiling point of acetophenone is only 2.2' C. less than that of phenylmethylcarbinol. Even though a t 10-mm pressure the difference in boiling points is increased to 10" C , extreme difficulty is still encountered in the fractionation of these two compounds.

The separation of purified acetophenone is greatly simplified, however, by a reduction in the concentration of phenylmethvl- carbinol in the process stream. This is achieved in the second phase of the acetophenone process, in which the concentration of carbinol is reduced from 32 to 6% by the catalytic dehydrogenation of a portion of the phenylmethylcarbinol to acetophenone.

~ ~ f i ~ i ~ ~ still in receivers. At the end of a run, the residue from the dehydrogenation reactor is burned as fuel. The mixture in thr product receivers, containing about 80% acetophenone, 6% phenylmethylcar-

binol, 14% ethylbenzene, and traces of water and residuc, is puniI)ed to a lmtch kettle.

A C E T O P H E N O N E -

P R O D U C T VAPOR

- - - T E T R A L l N

SPA R G E R --

RESIDUE] ~ T E T R A L I N O U T L E T O U T L E T

Figure 3. Dehydrogenation Reactor

The batch distillation is started after about 14,000 gallons of product, containing about 11,000 gallons of acetophenone, collected in the kettle. This 15,000-gallon vessel, made of Everdur, is heated by copper steam coils having a heat-transfer area of 050 square feet.

During the distillation, which takes 3 days to complete, the vapors pass from the kettle to IL copper, 24-tray bubble-cap


Dehydrogenation Reactor ( r igh t ) and Residue Stripping Still of Oxidation System (left)

Location Ethylbenzene feed line Catalyst feed tanks ( 2 ) Air feed line to each oxidation

Oxidation reactor blowoff line Oxidation reactor (2) Oxidation reactor, first Oxidation reactor, second Blowoff decanter Caustic feed tank Water line to water scrubber Water scrubber Still feed tank Still feed line Stripping still condenser Stripping still product and reflux

Head and side of stripping still

Stripping still column

Stripping still base

Refining still condenser Refining still Droduct and reflux

reactor (2)

lines

lines- . Side and base of refining still

Refining still column

Refining still base Batch residue still condenser Batch residue still vapor line

Batch residue still kettle Acetophenone-carbinol feed line Catalyst-feed mixing tank Dehydrogenation reactor and

vapor line Dehydrogenation reactor Batch kettle vapor line Batch column Batch column receivers ( 2 ) Batch column head and side

and kettle

Differential pressure Differential pressure Differential pressure P P P R f i l l P C - . _._ . Transmitter Differential pressure Differential pressure Differential pressure Differential pressure Differential pressure Differential pressure Differential pressure Differential pressure Pressure Differential pressure

Hg capillary

Differential pressure


Pressure Differential pressure

Hg capillary


Diffe.rentia1 pressure Pressure Transmitter

Differential pressure Differential pressure Differential pressure Transmitter

Differential pressure Pressure Differential pressure Differential pressure Hg capillary

TABLE 111. I N S T R U M E N T CONTI lOLb

Function Flow controller Liquid level indicator Flow controller

Pressure controller Temperature controller Liquid level controller Liquid level indicator Interface liquid level controller Liquid level indicator Flow controller Interface liquid level cantroller Liquid level indicator Flow controller Vacuum controller Reflux ratio controller

Temperature indicator and ' controller Differential pressure controller

Liquid level controller

Vacuum indicator Reflux ratio controllei

Temperature indicator and

Differential pressure controller controller

Liquid level indicator Vacuum indicator Temperature indicator

Liquid level indicator Flow controller Liquid level controller Temperature indicator

Liquid level contro!kr \ 'ar , ium contruller Differenrid uressure controller Liquid level indiratorv Teiiiprrature indicators

Regulated by Set flow

Set flow . . . . . . . . . . .

Set pressure Set temperature Set liquid level

. . . . . . . . . . . Set interface liquid level

. . . . . . . . . . . Set flow Set interface liquid level . . . . . . . . . . . Set flow Set absolute pressure Set reflux ratio

Set side column tempera-

Reset by side column tem-

Set base liquid level

ture

perature

. . . . . . . . . . . Set reflux ratio

Set side column tempera-

Reset by side column tern- ture

perature

. . . . . . . . . . . Set flow Set liquid level . . . . . . . . . . . Set liquid level Set absolute pressure Set column differential

Regulates Ethylbenzene feed

Air to each reactor

Blowoff to air Water t o coils Liquid flow from reactors

Water layer to sewer

Water to scrubber Water to sewer

. . . . . . . . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . .

. . . . . . . . . . . . . . . . . . Feed to ethylbenzene stripping still Nitrogen to vaoiium pump suction Product to receiver

Resets differential

Steam to reboiler

Feed to acetophenoIio-carbiilol rc- fining still

. . . . . . . . . . . . . . . . . Product to receivers

Resets differential

Steam to twin reboilers

. . . . . .

. . . . . .

. . . . . . . . . . . . . . . . . . . . . . . .

Feed to catalyst-feed mixing tank Feed t o dehydrogenation rractor

Tetralin supply to jacket Nitrogen to vacuum pump suction Steam to kettle coils

. . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . .


Shipping and Stor- age Facilities at Institute, W. Ira.

column operated a t 35 mm. of mercury absolute pressure and a t a reflux ratio of 10 to 1. During the first phase of the distillation, a mixture containing about 2000 gallons of ethylbenzene and 2000 gallons of acetophenone is collected in an intermediate receiver. The condensate stream is then switched to the product receiver for the collection of about 7000 gallons of commercial grade acetophenone.

When the freezing point of the distillate falls below a specified level, the fractionation is stopped. Usually the batch kettle then contains a mixture of about 2000 gallons of acetophenone and 1000 gallons of phenylmethylcarbinol. This residue, as xell as the mixture of ethylbenzene and acetophenone collected in the intermediate receiver, is returned to the oxidation system through the feed tank for the ethylbenzene stripping still.

The receiver for the refined acetophenone is lined with Bakelite phenolic resin to maintain the color stability of the product, otherwise impaired by the presence of iron. The refined material is pumped from the receiver into drums lined with the same Bake- lite resin and is then delivered to the warehouse for shipment.

In this process, the over-all efficiency of the conversion of ethylbenzene to acetophenone is about 85 %. The approximate use of utilities, per pound of acetophenone produced, is 0.04 l w . of electricity, 0.32 cubic foot of fuel gas, 27 gallons of river water, 7.0 pounds of steam, and 14.3 cubic feet of compressed air.

Freezing Point Determinations Are Important in Process Control

In the oxidation step, the extent of conversion of ethylbenzenc is determined from the specific gravity of the crude product hy the use of empirically derived tables. The addition of catalyst feed solution is regulated to permit the desired reaction rate to be attained with a minimum of catalyst This reaction rate is indicated by the amount of oxygen in the blow-off and by the stentii- ness of the cooling water demand on the reactors.

The temperature of the oxidation reactor is controlled by thc circulation of cooling water through the reactor coils. This temperature is maintained a t the lowest possible level that Rill give the desired reaction rate. This temperature level will also keep residue and acid formation at a minimum. The reaction pressure is maintained as high as possible to reduce the loss of organics in the blowoff. This pressure must be low enough, however, to enable the lvater added to the reactor and that formed by the reaction to be continuously swept out of the system-water that, would otherwise slow up the oxidation process.

In the caustic wash, the rate of caustic feed is regulated to produce an organic layer containing not more than 0.05% acidity as benzoic acid and an aqueous layer containing not more than 1.5% caustic. Higher concentrations of caustic tend to produce emul- sions.


I n the operation of the ethylbenzene stripping still, the rate of (or-methylbenzyl)ethylenediamine, a-methylbenzyl dimethyl- amine, and m-nitroacetophenone. The derivatives of phenylmethylcarbinol now being offered by Carbide include or-methylbenzyl ether, a-methylbenzyl Cellosolve, a-methylbenzyl Carbi- tol, and m-aminophenylmethylcarbinol.

Adequate Provisions Are Made to Ensure Safety of Workers

in the open.

steam flow through the heating coils is governed by the pressure drop across the column. This pressure drop, in turn, is controlled by the side-column temperature. During the distillation, the reflux ratio is set to give a minimum of oxidized materials in the overhead and a minimum of ethylbenzene in the bottom product. These conditions are checked periodically by the control laboratory, and the control points are reset if necessary. The acetophenone-carbinol refining still is controlled in essentially the same manner.

In the acetophenone process, operators rarely handle chemicals When they do, little or no hazard is involved if

reasonable care is exercised. The dan- ger of fumes is minimized by the use of

- - * P H E N Y L M E T H Y L - C A R B I N O L adequate ventilation. The plant is I I M A N U F A C T U R E equipped with a standard fire-alarm

system, in addition to an automatic sprinkler system that covers essentially all the outside equipment.

For their protection, plant operators B E N Z E N E M I X T U R E M I X T U R E R E F I N E D are required to wear goggles and rubber

gloves when needed. Gas masks and respirators are located near the process units and are used a t the operators'

ACETOPHENONE I--* M A N U F A C T U R E

J E T H Y L E N E AIR I HYDROGEN I

ETHYLATION

B E N Z E N E C A R B I N O L ACETOPHENONE I ,

S T Y R E N E

R E C Y C L E CARBINOL-

M I X T U R E A C E T O P H E N O N E

Figure 6. Rlaclc Diagram of Styrene Process

During the dehydrogenation, the acetophenone-carbinol feed rate to the catalyst-feed mixing tank is held constant. At the same time, the feed rate t o the reactor is automatically controlled by the liquid level in the mixing tank. The liquid level in the dehydrogenation reactor, in turn, governs the tetralin flow to the jacket.

I n the batch distillation of crude acetophenone, the low-boiling fraction is collected in an intermediate receiver. When the vapor temperature of acetophenone is approached, freezing points are determined hourly on the overhead product. As soon as the freezing point approaches the specification range, the distillate is collected in the product receiver. Later, as the freezing point drops, the reflux ratio is increased until further increases no longer bring about the desired rise in freezing point. At that time, the distillation is stopped.

Although in the acetophenone proces ments are located near the equipment, in a large, centralized control room. The location, type, function, and operation of these instruments are summarized in Table 111.

Carbide's specifications for acetophenone are indicated in Table IV. This material is somewhat below the purity of perfumery grade acetophenone, which Carbide does not attempt to produce. Perfumery grade acetophenone meets the following specifications: 99 t o 1 0 0 ~ o acetophenone by titration with hy- droxylamine: specific gravity 25"/25' C., 1.025 to 1.027; con- gealing point, 19.0' t o 19.5' C.; chloride by Beilstein flame test, none; color, water white; and odor, clean and floral.

Among the derivatives of acetophenone now being produced by Carbide are dypnone, a-methylbenzylamine, a-methylbenzyl monoethanolamine, a-methylbenzyl diethanolamine, N,N'-di-

TABLE IV. SPECIFICATIONS FOR CARBIDE AND CARBON CHEMICALS Co.'s ACETOPHENONE

Specific gravity a t 20°/200 C. 1 027-1.031 Distillation 760 mm. C

Minimud initial bdilinp'point 194 Maximum drv ooint 2116 -..

hcetophenone Gncentration (min.), wt. % 97.0 Acidity, max. calculated as benzoic acid (equivalent

0.02 Freezing point (min.),' C . 18.3 Color, APHA (max.) 15 platinum-cobalt

to 0.092 mg. KOH per gram sample), wt. %

Odor Suspended matter

Mild and aromatic Substantially free

discretion. Safety showers and eye- wash fountains are also available. Nec- essary medical care is provided by a

full-time doctor and by several nurses on duty a t the plant dispensary 24 hours a day.

Plant Personnel Are Familiar with Over-all Styrene Operations

Carbide's manufacture of acetophenone requires about one fourth the working hours of three technical personnel during a,

product run. In addition, two operators are required per shift. Ordinarily, these operators are men regularly assigned to the styrene plant. During an acetophenone run, the main job of process and quality control is handled part-time by a single

Operator Pour3 Scoop of Powdered Catalyst into Catalyst Feed Mixing Tank of Dehydrogenation System


Styrene Unit at Institute, W. Va.

analyst. h number of thc analyses arc also carried out by the shift operators.

Carbide’s sales of acetophenone and other chemicals are handled by about 80 technical representatives in 22 district offices scattered throughout the U. S. and Canada. In addition, there are three members of Carbide’s Fine Chemicals Division who are ready to provide technical assistance to current and potential users of acetophenone and other Carbide products.

Future Prospects for Acetophenone Depend on Developmental Work

Although today no individual product or group of products offers immediate promise of a substantial new market for acetophenone, the steady growth in almost all the uses of th is compound indicates clearly that the present upxlTard swing in acetophenone production mill continue. Particularly significant is the fact that since 1948 the production and use of acetophenone has increased roughly sixfold. The use of acetophenone as a solvent and as an intermediate in the manufacture of resins, pharmaceuticals, and other products is growing. Certainly, should the chemical industry’s requirements for acetophenone increase markedly in the years immediately ahead, Carbide wilI be in a position to help fill that need.

Back in 1943, Carbide chemists, referring to acetophenone and phenylmethylcarbinol, said in a formal research report: “It is possible that these materials may become very useful in their own right after the war, and it is suggested, therefore, that a review of the chemistry and uses of these chemicals be incorporated in a research program.”

Thus far, surely, the confidence of these researchers in the future of acetophenone has been more than justified. K o v to chemists mid chemical engineers goes the job of exploiting still further the potentialities of this up-and-coming ketone,

Literature Cited

(1) Conant , J. B., “Chemistry of Organic Compounds,” p. 410, S e w Yorli, Slacniillan Co., 1941.

Ib id . , p. 412. Denton, J. J., Turner , R. J., Keier, JT~ 13., Lawson, \’. ,\,,

and Schedl, H. P., J . Am. Chenz. Soc., 75, 2048-54 (1$14$)). Eaglesfield, Philip, U. 8. Pa ten t 2,197,101 (April 1 G , 1940). Emerson, IT. S., U. S. Pa ten t s 2,372,562 (March 27, 1945) arid

I b i d . , U. S. Pa ten t 2,394.674 (Fob. 12, 1946). Fieser, L. F., and Fieser, M., “Organic Chemistry,” 1). 580,

Ib id . , p. 583. Ibid. , p. 686. I b i d . , p. 739. I b i d . , p. 740. Friedel, C.. Jahresber. F’ortschr. Chena., 10, 270 (1857). Guest, H. R., and McNamee, R. T., 1;. S. I’atcnt 2 ,

I b i d . , U. S. P a t e n t 2,575,404 (Xov. 20, 1951). Iiarrer, Paul , ”Organic Chemistry,” p. 747, X c w Nortic-

man Publishing Co., 1938. Kirk, R. E., and Othmer. D. F., “Encyclopcdia of (:hcrnio;tl

Technology,” 7‘01. I, p. 95, Kew l-ork, Intersciencc E~icyclo- pedia, Inc . , 1947.

2,382,867 (8ug. 14, 1945).

New Vork, Intersqience Encyclopedia, Inc. , 1947.

(March 13. 1951).

I b i d . , p. 96. I bid., p. 97. Legerlots, T e l m u t , U. S. P a t e n t 1,932.347 (Oct . 24, 1933). Long, L. M., and Trou tman , H. D., J . A m . Chcm. Soc., 71, 24(i!)

Lucas, ST. E., and Emerson, W. S., U. 8. P a t e n t 2,444,816

Mills, E. J., Jr., U. S. Pa ten t 2,388,758 (Nov. 13, 1945). Richter , Victor von, “Chrmistry of the Carbon Compouiida,”

Vol. 111, S e w Yolk, Elsevier Publishing Co., 1946. Senseman, C. E., and Stubbs, J. J., ITD. EXG. CHEM., 25, 1286

(1933). Shrivel, L. C., C. S. Patent 2,399,395 (.April 30, 1946). Thorpe, J. F., “Dictionary of Applied Chemistry,” p, 71, Lon-

don, Longmans, Green and Co., 1937. Tilford, C. H., Shelton, It. S., and Van Campen, M. G., .Jr..

J . Am. Chem. Soc., 70,4001-8 (1948). C. S. Tariff Commission, “Synthetic Organic Chemicals, LT. S.

Production arid Sales,’’ TVashington, Government Printing Office, 1934, 1937, 1941, and 1948.

Wertheim, Edgar , “Textbook of Organic Chemistry,” p. 535, Philadelphia, Blakiston Co., 1939.

Young, D. hf . , Young, F. G., J r . , and Guest, 13. It., c‘. Y. Pa ten t 2,544,771 (March 13, 1951).

I b i d . , U. S. Pa ten t 2,375,403 (Nov. 20, 1951).

(1949).

(July 6, 1948).

acetophenone

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